Additions and Corrections
J . Am. Chem. Soc., Vol. 110, No. 7, 1988 2349
however, severe distortion of the helix;IL19consistent with our data (vide supra), DNA melting curves18show the relative lability of the duplex structure. Gel sequence analysisZoof the platinated oligomer (Table 11; Chart I) revealed a threefold increase in BLM-mediated damage at T6, which became the primary site of damage; a significant increase in cleavage at T,, was also noted. The emergence of TT as a preferred Fe(I1)-BLM cleavage site is unprecedented and provides an opportunity to identify those features in DNA that render the duplex susceptible to Fe-BLM-mediated modification. (19) (a) Macquet, J.-P.; Butour, J.-L. Eiochemie 1978, 60, 901. (b) Cohen, G. L.; Bauer, W. R.; Barton, J. K.; Lippard, S. J. Science (Washington, D. C.) 1979,203, 1014. (c) Cohen, G. L.; Ledner, J. A.; Bauer, W. R.; Ushay, H. M; Carvana, C.; Lippard, S.J. J . Am. Chem. SOC.1980,102, 2487. (d) Royer-Pokora, B.; Gordon, L. K.; Haseltine, W. A. Nucleic Acids Res. 1981, 9, 4595. (e) Ushay, H. M.; Tullius, T. D.; Lippard, S. J. Biochemistry 1981, 20, 3744. (f) Scovell, W. M.; Caponi, V. J. Biochem. Biophys. Res. Commun. 1982, 107, 1138. (20) Maxam, A. M; Gilbert, W. Methods Enzymol. 1980, 65, 499.
The observed changes in sequence specificity are entirely consistent with those reported earlier with the use of cis-DDP and much longer DNA fragments.I3 However, this study extends the earlier findings in important ways, including better definition of the spatial relationships between the Pt center and the BLM cleavage sites that leads to altered cleavage patterns, the demonstration that conformational alteration in DNA can lead to novel BLM-mediated DNA cleavage patterns, and the finding that platination does not alter the chemistry of DNA cleavage.
Acknowledgment. We thank Dr. Robert Hertzberg, S K & F Laboratories, for helpful discussions and for assistance with characterization of the oligonucleotides. This study was supported by PHS Grant CA38544, awarded by the National Cancer Institute, D.H.H.S., and by an American Cancer Society Scholar Grant to B.G. Registry No. BLM A,, 11 116-31-7; BLM, 11056-06-7; cis-DEP, 14096-5 1-6; 5’-d(CGCT,A,CGC), 113403-23-9; Pt[d(CGCT,A,G,)].d(C*T,A,GCG), 113403-26-2.
Additions and Corrections Determination of the Absolute Configurations of the Isomers of Triamminecobalt(m)Adenosine Triphosphate [J. Am. Chem. SOC. 1986, 108, 4167-41711. DAVIDC. SPECKHARD, VINCENTL. PECORARO, WILSONB. KNIGHT,and W. W. CLELAND* The assignments at the a-phosphate were inadvertently switched, so that endo isomers are really exo and vice versa. The p-phosphate assignments are correct. Thus isomers 1-4 (in order of elution from cycloheptaamylose) correspond to A-exo, A-exo, A-endo, and A-endo, respectively.
NitroethyleneYields N,N-Dihydroxyiminium-MethyliwnDication in Trifluoromethanesulfonic Acid. Dications Stabilized by Y Delocalization [J. Am. Chem. SOC.1987,109,70361. TOMOHIKO OHWADA, AKIKOITAI,TOSHIHARU OHTA,and KOICHISHUDO* Page 7038, reference 12 ( ~ 7 0 3 8 )should read as follows: In the case of planar conformations of N,N-dihydroxyiminium-methylium dication total energies obtained by MP2/ 6-3 lG*//4-31G and relative energies (in parentheses) are as follows: 17, -282.6202686 au (0.00 kcal/mol); 18, -282.6122271 au (5.05 kcal/mol); 19, -282.603404 au (10.58 kcal/mol). (The other descriptions are deleted. This correction, however, does not make any revision in the discussion and conclusion described in the text.)
